This brings back memories!

Several aeons ago when the iPhone first came out and writing apps became the new goldrush, I made an abortive attempt to teach myself Objective-C. I had an idea to make an app that did just this. Unfortunately I never got further than a command line proof of concept that returned the co-ordinates of the point on Earth directly opposite any location you entered --before deciding me and Objective-C just weren't going to get along.

Good to see my 'killer app' idea being brought to life, all these years later. Great minds... and all that.